Microprocessor based protection and control relays (also called IEDs) that are used in the transmission and distribution network nowadays typically come with a LCD display. While most IEDs are used in electrical substations that have a controlled environment, some are used in non-controlled, outdoor environments. These relays and the components inside them can be subjected to wide swings in temperature as well as extremes of temperature on a daily basis. These extremes are known to cause failures of the continuously powered LCD display module over time. Such failures are bothersome in recloser applications as the cost to repair is high due to the nature of installation of these devices (in a widely distributed area and near high voltage power lines).
It is possible to overcome the above limitation by using higher grade components. However, this adversely impacts the cost of the LCD display module.
Thus, there is a need to extend the life of a display in an IED used outdoors by powering the display off or by reducing power thereto when not in use.